[llvm] [AMDGPU] Add function attribute to control TBUFFER combining (PR #156454)

[Matt Arsenault via llvm-commits]

arsenm wrote:

I think the only issue with a module flag would be if you care about having different entry points in the same module with different behavior. If this is an attribute this needs more work to properly handling inlining with mixed modes 

Also I'm still not clear how this differs from the the relaxed-oob-mode feature. Can these be merged into one? In any case I'd like to see those use identical mechanisms before introducing another knob 

https://github.com/llvm/llvm-project/pull/156454